This invention relates to an underground tank and a process for constructing same for storage of petroleum or liquified gases.
In general, it has been common practice in the construction of an underground tank to excavate earth while pumping accumulation of water due to seepage according to a well point construction process, deep well construction process or the like, and then to construct the underground tank in the excavated area. However, unless ground water is continuously pumped out after the construction of the tank, an upward pressure of water acts on the bottom portion of the underground tank. Thus, if the surrounding water table is relatively high, the floor slab of the tank could be cracked by this pressure.
Prior efforts to cope with this problem include a proposed underground tank, wherein there is provided a water collecting sump area under the bottom slab from which collected ground water is pumped out. However, ground water continuously flows from the surrounding ground into the collecting sump and hence pumping means must be maintained all the time, with the resulting expenditure of considerable time and effort and expense. Furthermore, in the event that the pumping means malfunctions, the tank is endangered with flotation and cracking stresses. Furthermore, to remove water from beneath the bottom slab of a tank requires complicated apparatus which is difficult to service.
It is therefore an object of the invention to provide an underground tank and a process for constructing same, in which ground water is conveniently and expeditiously controlled.
It is another object of the invention to provide an underground tank against which flotation pressures are minimized.
It is another object of the invention to provide a process for constructing an underground tank in which ground water immediately adjacent the construction site is isolated from ground water comprising the general water table.
It is another object of the invention to so minimize water seepage around an underground tank so that the failure of a pumping means does not result in dangerous flotation pressures building up around the tank.
It is another object of the invention to provide a process for constructing an underground tank for storing liquified gas, in which the surrounding ground is frozen to isolate the tank from the ground water.
It is still another object of the present invention to provide an economical process for constructing and maintaining an underground tank.
It is yet another object of the present invention to provide a process for constructing an underground tank in which in the absence of a water impermeable foundation strata of sub-soil, a water impermeable foundation may be artificially constructed with ease.
With the foregoing and other objects and features of the invention which will become evident from a reading of this specification, the invention consists of certain novel features of design and arrangement as illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the form, proportion, size and minor details of the invention may be made without departing from the spirit, or sacrificing any of the advantages, of the invention.
For the purpose of facilitating an understanding of the invention, there is illustrated in the accompanying drawings preferred embodiments thereof, from an inspection of which when considered in connection with the following description, my invention, its mode of construction, assembly and application and many of its advantages, will be readily understood.